Time-element selective relay



Sept. 24, 1929. SLEEPER 1,729,404

TIME ELEMENT SELECTIVE RELAY Filed Sept. 23, 1921 2 Sheets-Sheet 1 :ATTORNEY Sept. 24, 1929. SLEEPER 1,729,404

TIME ELEMENT SELECTIVE RELAY FiledSept. 25. 1921 2 Sheets-Shea; 2

WITNESSES: INVENTOR Ham e 25/66 @7? BY y P ATTORNEY Patented Sept. 24, 1929 UNITED STATES PATENT OFFICE HAEVEY P. SLEEPER, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRTC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA TIME-ELEMENT SELECTIVE RELAY Application filed. September 23, 1921.

My invention relates to electrical protective devices and particularly to relays.

One object of my invention is to provide a time-limit relay having electrical means for obtaining its time-limit functions.

Another object of my invention is to pro vide a relay, of the above-indicated character, that shall have an inverse time limit for values of current up to a predetermined value and a definite or unvarying minimum time limit for all values of current exceeding the predetermined value.

Another object of my invention is to provide a relay, of the above-indicated character, that shall embody means for controlling the direction in which the movable element thereof shall be actuated.

Another object of my invention is to provide a relay, of the above-indicated character, that shall selectively operate to disconnect a faulty feeder circuit of two feeder circuits to which the relay is connected.

A further object of my invention is to provide a directional selective balance relay of the induction type embodying an inverse time function in its operation.

United States Patent No. 1,286,415, issued Dec. 8, 1918, to F. E. Ricketts, and assigned to the Westinghouse Electric and Manufacturing Company, discloses an induction disctype relay embodying an inverse time function in its operation that is obtained and controlled by means of a saturable transformer that operates to control the torque developed in the relay.

The saturable transformer permits a torque to be developed in the relay that is proportional to the value of the current traversing the relay up to a predetermined value at which the transformer becomes saturated. When the current traversing the relay exceeds the value at which the transformer becomes satu rated, the torque developed in the relay re mains constant, irrespective of increase in the value of current traversing the relay, by reason of the regulating effect of the saturated transformer.

United States patent to F. E. Ricketts,

1,594,117, July 27, 1926, and assigned to the Westinghouse Electric and Manufacturing Serial No. 502,596.

Company, discloses a differential balance relay that is instantaneous in its operation to disconnect one of two feeder circuits to which it may be connected when that circuit becomes faulty.

In practicing my invention, I employ the selective relay that is disclosed in the abovementioned Ricketts application and provide therefor a saturable transformer or torque compensator, as it is commonly known, and which is described in the above-mentioned Ricketts patent, whereby the relay may be caused to embody both a directional and a time-limit feature.

Figure 1 of the accompanying drawings is a diagrammatic view of an electrical circuit containing a relay embodying my invention;

Fig. 2 is a graph containing two curves illustrating the operation of the relay for various conditions, and Figs. 3, 4 and 5 are diagrammatic views of a plurality of electrical circuits, illustrating different methods of connecting the relay to the feeder circuits.

In Fig. 1, a source 1 of electromotive force supplies energy to a circuit 2 from which energy is supplied to a plurality of feeder circuits 3 and 4 through two circuit interrupters 5 and 6, respectively. The interrupters 5 and 6 are respectively provided with trip coils 7 and 8, the respective circuits of which are controlled by a selective relay 9, in combina tion with a control source 10 of energy. Two current transformers 11 and 12 are respec tively connected in circuit with a conductor of the feeder circuits 3 and 4 and are employed to energize and control the operation of the relay 9.

The relay 9 comprises, in general, a magnetizable core member 13, a rotatable armature 14, a polarizing winding 15 and a selective winding 16 that co-operates with the winding 15 to actuate the rotatable armature 14. The armature 14 controls, by means of the shaft upon which it is disposed, the engagement of a movable contact member 17 and two stationary contact members 18 and 19, respectively.

The relay 9 further comprises a torque compensator 20 that is connected between the current transformers 11 and 12 and the winding to control the energization of the latter. The torque compensator, or saturable transformer 20, comprises a core member 21, two primary windings 22 and 23 and a secondary winding 24.

The primary windings 22 and 23 of the transformer are connected in series with the current transformers 11 and 12, in a cumulative sense, in order to effect substantial polarization of the core member 21 and, consequently, of the secondary winding 24. The winding 15 of the relay 9 is, consequently, continuously energized in one direction.

The winding 16 is connected across the auxiliary circuit including the current transformers and the primary windings and, while the currents traversing the circuits 3 and 4, and, consequently, the current transformers 11 and 12 are balanced, no current traverses the winding 16. In the relay, as manufactured, the winding 16 is provided with a plurality of taps to permit adjustment of the setting at which the relay shall operate.

Upon the occurrence of an unbalance, however, between the currents traversing the feeder circuits 3 and 4, current is caused to traverse the winding 16 in a direction depending upon which of the circuits 3 and 4 is traversed by a greater value of current.

Thus, if a fault should occur on the circuit 3, as at the point A, .current would be caused to traverse the winding 16 in the direction indicated by the dotted arrow A, whereas, if a fault should occur on the cir cuit 4, as at the point B, current would be caused to traverse the winding 16in the direction of the dotted arrow B.

The directional feature of the relay 9 is thus controlled by the co-operation of the fluxes that are produced by the windings 15 and 16, respectively. The winding 15 produces a constant flux in one direction, and the minding 16 produces a flux, only upon the occurrence of unbalanced current conditions, in a direction depending upon which of the feeder circuits is faulty.

lVhen the currents traversing the circuits 3 and 4 exceed a predetermined value that causes the core member 21 of the transformer 20 to he worked above the knee of its saturation curve, the voltage induced in the secondary winding 24 does not increase in proportion to the increase in the value of the currents traversing the primary windings 22 and 23, but remains substantially constant. Thus, a definite time element in the operation of the relay is produced by means of the saturable transformer 20 when .the current traversing the primary windings thereof exceeds a predetermined value corresponding to the saturation point of its core member.

When a fault occurs on the circuit 3 that causes an unbalance between the currents ers 11 and 12, the windings 15 and 16 cooperate to effect the turning of the armature 14 to effect engagement between the contact members 17 and 18. The trip coil 7 is thereupon en-crgized to actuate the interrupter 5 to disconnect the faulty circuit 3 from the supply circuit 2.

Upon the disconnection of the circuit 3 and the consequent de-energization of the current transformer 11, the current transformer 12 alone operates to energize the relay 9. An advantageous feature of the relay, when operating under such conditions, is illustrated by the curve in Fig. 2.

Since the operation of the relay 9 requires energization of the winding 15 to a predetermined degree, the current transformer 12 must energize the saturable transformer to the degree to which it was previously energized by both current transformers 11 and 12. Thus, when the current transformer 11 is tie-energized by reason of the disconnection of the feeder circuit 3, the circuit 4 must be traversed by twice the value of current that previously traversed that circuit in order to energize the transformer 20 to the degree required for the operation of the relay 9.

Thus, where a current of 5 amperes in each of the current transformers 11 and 12 sufficiently energizes the current transformer 20 to maintain the winding 15 of the relay 9 energized to a predetermined degree, a current of 10 amperes is required in the current transforniier 12 after the current transformer 11 is de-energized. The relay 9 is thus automatically adjusted to protect the circuit 4 for an increased overload that would immediately result upon the disconnection of the feeder circuit 3.

This automatic adjusting feature obviates the necessity of auxiliary devices for preventing the disconnection of the normal feeder circuit 4 immediately after the disconnection of the faulty circuit 3, as has been necessary heretofore in protective systems for balanced feeder circuits.

The curve 26 in Fig. 2 illustrates the inverse time clement feature of the relay and shows the constant time limit of the relay when the current traversing the primary windings of the transformer 20 saturates the core member 21.

The operation of the relay 9 is not limited to the cumulative action of the current transformers, as just described, but may also be effected by differentially connecting the transformers 11 and 12 to the windings 22 and 23 of the torque compensator 20. When the current transformers 11 and 12 are thus connected, the effects of the windings 22 and 23 are differential and the winding 24 is therefore energized only upon the occurrence of an unbalance between the current transformers 11 and 12, whereas the windtraversing the respective current transforming 16 of the relay is continuously energized.

In Fig. 3 is illustrated a modified form of the relay shown in Fig 1, that embodies two torque compensators and 26 which are provided with primary windings 27 and 28, respectively. The windings2'? and 28 are connected in series with the current transformers -11 and 12, and the secondary windings 29 and of the torque compensators 25 and 26, respectively, are connected to windings 31 and 32 that are disposed on the upper poles of the magnetizable member 13. The winding 16 that is disposed on the lower pole of the magnetizable member is connected across the transformer circuit and is energized only upon the occurrence of an unbalance between two circuits 3 and 4;. In the relay that is shown in Fig. 3, the magnetic circuits of the compensating elements, that are energized by the current transformers, are separate.

In Fig. 4 is illustrated a modified form of the relay shown in Fig. 1, comprising a single torque compensator 3 1 that energizes the winding 15 in a manner similar to that ex plained in connection with the relay in Fig. 1. Instead, however, of the winding 16 of the relay shown in Fig. 1, two windings and 36 are provided which are respectively energized from the corresponding current transformers 11 and 12. In this relay, the magnetic circuit of the torque compensator is common to both circuits, but the electrical circuits including the windings 35 and 36 are separate.

In Fig. 5 is illustrated another modification of the relay embodying my invention in which both the magnetic circuits and the electrical circuits energized by the respective current transformers 11 and 12 are separate from each other. Two torque compensators 25 and 26 are employed to energize windings 31 and 32-, as shown in the relay that is illus trated in Fig. 3. Two windings 35 and 36 are also provided for the lower pole, as shown in the relay that is illustrated in Fig l. By means of the arrangement illustrated in Fig. 5, both the magnetic and the electrical circuits energized by the current transformers are maintained separate from each other.

It will be observed that my invention contemplates a differential selective relay that disconnects one of the two feeder circuits when that circuit becomes faulty, and that embodies a time element in that operation, and that further operates as an overload relay with a higher setting to protect the normal feeder circuit from the excessive current that will be caused to traverse the same by reason of the disconnection of the faulty parallel feeder circuit.

My invention is not limited to the specific construction or arrangement illustrated but may be variously modified within the spirit and scope of the invention, as set forth in the appended claims.

I claim as my invention:

1. A directional selective balance relay embodying controlling means operative in two directions and means for obtaining a definite minimum time of operation of the controlling means.

2. A directional selective balance relay embodying controlling means operative in two directions and means including a satu rating transformer for controlling the direction and the time of operation of the controlling means.

3. A directional selective balance relay embodying an induction disc element operative in two directions and means including a saturating transformer for controlling the time of operation of the disc element in each direction.

4. A directional selective balance relay embodying an induction disc element operative in two directions and means connected to the relay for controlling the direction and the time of operation of the disc element.

5. A directional selective balance relay or plurality of electric circuits embodying elective means operative for controlling the ircuits and means including a saturating ransformer for controlling the selection and he time of operation of the selective means.

6. A directional selective balance relay for a plurality of electric circuits embodying selective means comprising a plurality of windings and an armature con trolled thereby operative for controlling the circuits and means energized from the plurality of cir cuits for controlling the selection and the time of operation of the selective means.

7. A directional selective balance relay for a plurality of electric circuits embodying selective means operative for controlling the circuits and means differentially energized from the plurality of circuits for controlling the selection and the time of operation of the selective means in accordance with the respective conditions of the circuits.

8. A directional selective balance relay for a plurality of electric circuits embodying selective means operative for controlling the circuits, means for controlling the operation of the selective means to impart a definite minimum time characteristic thereto and means for energizin the controlling means from the circuits.

9. A relay comprising a magnetizable core member having two windings disposed thereon, an armature and a transformer connected between the two windings, the transformer comprising means for controlling the direction of rotation of the armature and the torque for actuating the same.

10. A relay comprising an armature, a main winding, an auxiliary winding and a transformer associated with said windings, the tr. nsformer being adapted to control th direction of the current traversing one of the windings to control the direction of the movement of the armature.

11. A relay comprising an ll "l), a main winding, an auxiliary wind 7 means connected between the windings to co trol the direction and, under certain tions, the magnitude of current t irough he winding whereby a predetermined directive torque is exerted upon the armature 12. In a system of distribution, the combination with two parallel-connected feeder circuits, of rela for selectively protecting the two circuits and for protecting one of the circuits after the other has become disconnected.

18. In a system of distribution, the combination with two parallel-connectcd feeder circuits, of a balance relay so connected to said circuits as to be operated selectively upon a predetermined overload current in either of said feeder circuits and, after the disconnection of the faulty circuit, to be operated upon a relatively larger current in the remaining circuit.

14. In a system of distribution, the combi nation with two parallel feeder circuits and circuit-interrupters therein, of a relay so connected to said circuits as to be ope ated upon a predetermined overload current in one of said circuits when both circuits are operating in parallel and to be operated upon a relatively larger current in said one of said circuits when the other of said circuits has been interrupted.

15. In a system of distribution, the combination with two parallel feeder circuits, of an induction relay having salient pole pieces, windings thereon and an armature member controlled thereby, and a saturating transformer having two primary windings energized in accordance with the currents flowing in said circuits, and a secondary winding, said relay having two inductively-related windings in series with the primary windings of said transformer and a third winding connected to the secondary winding of said transformer.

16. In an electrical distribution system provided with two parallel-connected feeder circuits, the combination with a circuit-breaker and a current-transformer in each circuit, of a protective system for the circuit breakers energized from the current transformers and comprising a relay provided with an induction disc and at least two windings for establishing a moving magnetic field to move the disc, and means for modifying the value of the current supplied to one winding and the relation of such current to that in another winding whereby the direction of the resultant magnetic field will selectively operate the relay disc to operate the circuit breaker in the faulty line upon theoccurrence of an abnormal condition effecting an unbalance between the currents in the two feeder circuits.

17. A protective circuitfor two parallel- HARVEY P. SLEEPER. 

